You shall be greatly rewarded for your efforts at Fort Amol, my servant. It pleases me to hear that the alchemical elixirs you discovered in the Daedric ruins have proven to be so useful. Who would have imagined an elixir that allows you to steal the form of anyone who drinks it? Remarkable!
And the other potion? The poison? Make sure that my dear brother gets a full dose of the deadly liquid. No one deserves such a fate more than my beloved, conniving, cheating, too-smart-for-his-own-good brother Jorunn.
When everything has been dealt with, meet me at Skuldafn. We have one last thing to deal with before I can reclaim my kingdom.